Pre-drilling deep, complex, sub-salt wells from a spacious 5th generation semi-submersible rig is a challenge, but drilling these wells from a spar rig adds new meaning to “challenge”.
BP’s Mad Dog field is located south of the Port of Fourchon about 150 miles in Green Canyon 782 and is in 4600’ of water. The original discovery well was drilled in 1998. Three appraisal wells were drilled from 1999 to 2001. Mad Dog was sanctioned as a Spar Development and a pre-drill program commenced in November of 2002 with the Diamond Offshore Ocean Confidence and was completed August of 2003. The Mad Dog Spar arrived, 4 wells were completed, and first oil was achieved in January 2005.
At the time of writing this abstract the Mad Dog #9 well, which is the first “grassroots” well to be drilled from the Mad Dog Spar, is 205 days from spud. This SPE Drilling Study Group Presentation will address topics such as, riserless drilling from the spar, spar rig capabilities and limitations, environmental sensitivities, Mad Dog well design to accommodate annular pressure build-up, salt drilling, sub-salt tar, and an array of contingencies to include solid expandable tubulars.